Open all Levels
In the main menu of IGI2:CS Press Left Ctrl + Left Shift + F9 at the same time.

Disable Enemies
Find all the folder named "ai" in the game's folder. Then rename them with any other name. Now when you run then game, all the anemies in the game will stood as a model. But be care ful of tanks and other machineguns they are still active.

Cheat Mode
Type nada at the main menu followed by one of the following codes to activate the corresponding cheat function.